Real-world data on adult AML with FLT3-ITD mutation from the Thai Acute Leukemia Working Group (TALWG)

Thanawat Rattanathammethee^1*Ekarat Rattarittamrong¹Chinadol Wanitpongpun²Smith Kungwankiattichai³Weerapat Owattanapanich³Chantiya Chanswangphuwana⁴Chantana Polprasert⁴Thanakrit Piyajaroenkij⁵Pimjai Niparuck⁵Supawee Saengboon⁶Wasithep Limvorapitak⁶Panachai Silpsamrit⁷Kannadit Prayongratana⁷Chantrapa Sriswasdi⁷Jakrawadee Julamanee⁸Pirun Saelue⁸Aimwipa Sasakul⁹Dusit Jit-ueakul¹⁰Chajchawan Nakhakes¹¹Adisak Tantiworawit¹

• ¹Division of Hematology, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand, Chiang Mai, Thailand
• ²Division of Hematology, Department of Internal Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand, Khon Kaen, Thailand
• ³Division of Hematology, Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand, bangkok, Thailand
• ⁴Division of Hematology and Center of Excellence in Translational Hematology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand, Bangkok, Thailand
• ⁵Division of Hematology, Department of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand, Bangkok, Thailand
• ⁶Division of Hematology, Department of Internal Medicine, Thammasat University, Pathumthani, Thailand, Pathumthani, Thailand
• ⁷Division of Hematology, Department of Internal Medicine, Phramongkutklao Hospital and College of Medicine, Bangkok, Thailand, Bangkok, Thailand
• ⁸Hematology Unit, Division of Internal Medicine, Prince of Songkla University, Hat Yai, Songkhla, Thailand, Songkhla, Thailand
• ⁹Division of Hematology, Department of Medicine, Chulabhorn Hospital, Bangkok, Thailand, Bangkok, Thailand
• ¹⁰Division of Hematology, Department of Medicine, Faculty of Medicine, Vajira Hospital, Navamindradhiraj University, Bangkok, Thailand, Bangkok, Thailand
• ¹¹Division of Hematology, Department of Medicine, Rajavithi Hospital, Bangkok, Thailand, Bangkok, Thailand

Background: FLT3-ITD mutations are among the most common genetic alterations in acute myeloid leukemia (AML) and are associated with poor clinical outcomes. However, data from low-and middle-income countries remain limited. This study aimed to investigate the prevalence, clinical characteristics, treatment patterns, and outcomes of adult AML patients with FLT3-ITD mutations in Thailand.We analyzed data from 360 adult patients with newly diagnosed AML, prospectively collected from 11 institutions nationwide between 2016 and 2023. FLT3-ITD mutational status, clinical features, response to therapy, and survival outcomes were compared between FLT3-ITD and FLT3-wild-type patients.Results: FLT3-ITD mutations were detected in 28.1% of patients. FLT3-ITD patients had higher white blood cell counts, bone marrow blast percentages, and NPM1 co-mutations compared to wild-type FLT3. Induction chemotherapy rates were similar, but FLT3 inhibitor use was nearly absent. Complete remission was achieved in 55.7% of FLT3-ITD patients versus 66.5% in wildtype FLT3. Median overall survival was significantly shorter in the FLT3-ITD group (8.8 vs. 13.2 months, p=0.039), while relapse-free survival was not significantly different. Multivariable analysis confirmed FLT3-ITD mutation as an independent predictor of poor overall survival.In this nationwide real-world study, FLT3-ITD AML was associated with inferior outcomes despite comparable induction therapy. Limited access to FLT3-targeted treatments and stem cell transplantation may contribute to these disparities. Our findings highlight the urgent need for expanding access to molecular testing and targeted therapies in resource-limited settings.